Several types of heavy machines incorporate articulated frames. Examples of articulated frames include wheeled tree harvesters, wheeled loaders, articulated compaction machines and motor graders. It is advantageous under some circumstances to prevent articulation of the machine. An articulation lock preserves the relative position of the parts of the machine frame: generally a two-part frame and prevents articulation.
As a class, heavy machines are those frequently used for earth movement, civil works, agriculture, and construction applications.
In the case of a motor grader, an operator may wish to prevent articulation to complete certain operations. Since the motor grader has steerable front wheels, directional control of the motor grader can be maintained while articulation is limited. On the machines making use of articulation for steering, the articulation lock may be used while transporting the heavy machine by truck or rail. Further utility arises from use of the articulation lock by service mechanics when working on the vehicle, particularly when working in the vicinity of the articulated joint.
Known articulation locks make use of an upper, lower pad-eye on a first portion of the articulated frame and a center pad-eye on a second portion of the articulated frame with an appropriately sized pin. In the locked position the pin is placed through the upper, center and lower pad-eye to prevent articulation of the portions of the vehicle frame. While for convenience of explanation and illustration the invention is described in terms of an upper, lower, and center pad-eyes, an articulated joint may comprise a plurality of pad-eyes not dissimilar from a hinge.
Steering of articulated heavy vehicles is generally accomplished by hydraulic cylinders positioned so as to alternatively push or pull one frame part to angularly rotate the frame part about a hinge point. The hinge point generally comprises a vertical hinge pin(s) in a plurality of pad-eyes located along the vehicle front-to-rear mid-line.
The articulation lock is generally located laterally from the hinge point at a location approximately orthogonal to the vehicle front-to-rear mid-line. Known pins 40 incorporate a through-hole and a roll pin extending beyond the diameter of the lock pin, or a washer 42 welded to the top of the lock pin or a similar feature used as a retainer to keep the pin in the articulation lock from falling through the articulation lock because the influence of gravity. Known retaining features such as roll pins are incapable of removal from the lock pin without requiring hand tools such as a hammer and drift punch. While such features serve the function of resisting the influence of gravity on the lock pin, removal of the lock pin can be complicated by the presence of the retainer.
When it is desired to remove the lock pin having a retainer feature it is necessary to lift the pin vertically as the retainer feature performs its function to prevent the lock pin from falling downward out of the pad-eyes forming the articulation lock. Unless the articulated frame members are positioned in near perfect alignment, the articulation lock pin may be held in position by the transverse pressure applied across the pad-eyes. Thus for a single individual, removal of the lock pin may involve incrementally adjusting the steering of the heavy vehicle in effort to find a position where no transverse pressure is applied to the lock pin. This effort to locate a position of no transverse pressure may involve a few, or many trips from the operator station, back to the location of the lock pin, only to be frustrated that the pin was not movable by muscle power.
Alternatively, removal of the lock pin may be a two-person operation with an operator incrementally changing the position of the articulated frames by operating the hydraulic steering mechanism, while an assistant maintains vertical force on the lock pin to remove the same. While this two-person sequence may be faster as it saves the operator's time and effort of repeatedly climbing from the lock pin location to the operator station, it suffers from the disadvantage of requiring an assistant and more importantly places the assistant in a vulnerable position on a possibly wiggling heavy vehicle.
The instant invention provides an improved articulation lock primarily by providing an improved lock pin retaining device and system. Removal of the retainer may be accomplished without the need for tools. The articulation lock may be removed with the assistance of gravity, without repeated operator effort climbing from the lock pin location to the operator station, and without placing an assistant in a hazardous location on the heavy machine.